Remote X11vnc session unusable due to crash in gnome-shell when disconnecting HDMI monitor under Ubuntu Desktop 18.04 LTS

[pataluna]

Expect to happen: I can use X11VNC when the monitor is disconnected.

What happens instead: remote X11vnc session unusable due to crash in gnome-shell when disconnecting HDMI monitor under Ubuntu Desktop 18.04 LTS

I'm using a stable system that works fine when the monitor is connected; also X11VNC works fine.

But I want to access the GUI remotely via X11VNC when the HDMI monitor is disconnected then the system is not usable (lots of gnome-shell errors in syslog) and sometimes the gnome-shell will also segfault (the segfault is not in this bugreport). The X11 remote viewer is full of clutter (see screencast).

Please see below for the syslog entries when disconnecting the monitor with no X11VNC active, and the syslog entries when the monitor is disconnected and starting X11VNC.

Gist: https://gist.github.com/pantaluna/c4f69f367611c596d10919f3c80e1a0d

X. VIDEO: X11VNC monitor disconnected.
https://www.dropbox.com/s/a8jjnw14uhtibzk/ubuntu1804-x11vnc-disconnected-monitor-fatal.mp4?dl=0

X. System
https://gist.github.com/pantaluna/c4f69f367611c596d10919f3c80e1a0d
- Ubuntu Desktop 18.04 LTS (latest updates until Jul19,2018 14:00h).
- Intel HD Graphics 530

$ lsb_release -rd
    Description: Ubuntu 18.04 LTS
    Release: 18.04

$ root@s3black:~# apt-cache policy gnome-shell
gnome-shell:
  Installed: 3.28.2-0ubuntu0.18.04.1
  Candidate: 3.28.2-0ubuntu0.18.04.1
  Version table:
 *** 3.28.2-0ubuntu0.18.04.1 500
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     3.28.1-0ubuntu2 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages

$ lspci -nnk | grep -i -A3 "vga" | grep 'in use'
    Kernel driver in use: i915

$ lshw -C video
  *-display
       description: VGA compatible controller
       product: HD Graphics 530
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 06
       width: 64 bits
       clock: 33MHz
       capabilities: pciexpress msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:127 memory:de000000-deffffff memory:c0000000-cfffffff ioport:f000(size=64) memory:c0000-dffff

X. GIST: Syslog entries when disconnecting the HDMI cable.
egrep --ignore-case "gnome|hdmi" /var/log/syslog
    Jul 19 14:37:53 s3black kernel: [ 943.153341] i915 0000:00:02.0: HDMI-A-1: EDID is invalid:
    Jul 19 14:37:53 s3black kernel: [ 943.153347] [00] BAD 00 ff ff ff ff ff ff 00 ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153349] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153351] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153353] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153354] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153356] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153358] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:53 s3black kernel: [ 943.153360] [00] BAD ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
    Jul 19 14:37:55 s3black gnome-shell[2017]: JS WARNING: [resource:///org/gnome/shell/ui/workspaceThumbnail.js 903]: reference to undefined property "_switchWorkspaceNotifyId"
    Jul 19 14:37:56 s3black gnome-shell[2017]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
    Jul 19 14:37:56 s3black gnome-shell[2017]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
    Jul 19 14:37:56 s3black gnome-shell[2017]: JS ERROR: TypeError: this._monitor is undefined#012DockedDash<._resetPosition@/<email address hidden>/docking.js:1089:17#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012DockedDash<._init@/<email address hidden>/docking.js:416:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012_Base.prototype._construct@resource:///org/gnome/gjs/modules/_legacy.js:18:5#012Class.prototype._construct/newClass@resource:///org/gnome/gjs/modules/_legacy.js:114:32#012DockManager<._createDocks@/<email address hidden>/docking.js:1717:20#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012DockManager<._toggle@/<email address hidden>/docking.js:1663:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe2d6c30 StButton.app-well-app ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fbe39c40 StWidget:last-child first-child ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe2d6c30 StButton.app-well-app ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fbe39c40 StWidget:last-child first-child ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fd5fb440 StWidget.app-well-app-running-dot:first-child] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe2d6c30 StButton.app-well-app ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fbe39c40 StWidget:last-child first-child ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe522d50 StBin.overview-icon] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe2d6c30 StButton.app-well-app ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fbe39c40 StWidget:last-child first-child ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe522d50 StBin.overview-icon] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe520050 ShellGenericContainer:last-child first-child] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe2d6c30 StButton.app-well-app ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fbe39c40 StWidget:last-child first-child ("33")] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe522d50 StBin.overview-icon] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe520050 ShellGenericContainer:last-child first-child] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: st_widget_get_theme_node called on the widget [0x5650fe51cf50 StBin:last-child first-child] which is not in the stage.
    Jul 19 14:37:56 s3black gnome-shell[2017]: clutter-actor.c:10049: Actor 'dashtodockDashScrollview' tried to allocate a size of 66.00 x -64.00
    Jul 19 14:37:56 s3black gnome-shell[2017]: clutter-actor.c:10049: Actor 'dashtodockDashScrollview' tried to allocate a size of 66.00 x -64.00
    Jul 19 14:37:56 s3black gnome-shell[2017]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
    Jul 19 14:37:56 s3black gnome-shell[2017]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
    Jul 19 14:37:56 s3black gnome-shell[2017]: JS ERROR: TypeError: this._monitor is undefined#012DockedDash<._resetPosition@/<email address hidden>/docking.js:1089:17#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22
    Jul 19 14:37:56 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:37:56 s3black gnome-shell[2017]: message repeated 6 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:37:56 s3black gnome-shell[2017]: JS ERROR: TypeError: this._monitor is undefined#012DockedDash<._updateBarrier@/<email address hidden>/docking.js:963:1#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012DockedDash<._initialize@/<email address hidden>/docking.js:444:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22
    Jul 19 14:37:56 s3black gnome-shell[2017]: clutter-actor.c:10049: Actor 'dashtodockDashScrollview' tried to allocate a size of 66.00 x -64.00
    Jul 19 14:37:56 s3black gnome-shell[2017]: setup_framebuffers: assertion 'height > 0' failed
    Jul 19 14:37:56 s3black org.gnome.Shell.desktop[2017]: Window manager warning: Overwriting existing binding of keysym ff09 with keysym ff09 (keycode 17).
    Jul 19 14:37:56 s3black org.gnome.Shell.desktop[2017]: Window manager warning: Overwriting existing binding of keysym ff09 with keysym ff09 (keycode 17).
    Jul 19 14:37:56 s3black gnome-shell[2017]: clutter-actor.c:10049: Actor 'dashtodockDashScrollview' tried to allocate a size of 66.00 x -64.00
    Jul 19 14:37:56 s3black gnome-shell[2017]: setup_framebuffers: assertion 'height > 0' failed
    Jul 19 14:37:56 s3black gnome-shell[2017]: message repeated 3 times: [ setup_framebuffers: assertion 'height > 0' failed]

X. GIST: Syslog entries when opening a remote X11VNC session and doing some GUI interactions with the mouse (the mouse clicks on menu's do not work anymore).
https://gist.github.com/pantaluna/c4f69f367611c596d10919f3c80e1a0d
egrep --ignore-case "gnome|hdmi" /var/log/syslog
    Jul 19 14:44:31 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:33 s3black gnome-shell[2017]: message repeated 335 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:33 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:34 s3black gnome-shell[2017]: message repeated 167 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:35 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:35 s3black gnome-shell[2017]: message repeated 55 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:36 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:36 s3black gnome-shell[2017]: message repeated 83 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:36 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:39 s3black gnome-shell[2017]: message repeated 244 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:39 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:40 s3black gnome-shell[2017]: message repeated 111 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:41 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:43 s3black gnome-shell[2017]: message repeated 272 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:44 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:48 s3black gnome-shell[2017]: message repeated 321 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:49 s3black gnome-shell[2017]: meta_window_is_on_primary_monitor: assertion 'window->monitor' failed
    Jul 19 14:44:52 s3black gnome-shell[2017]: message repeated 580 times: [ meta_window_is_on_primary_monitor: assertion 'window->monitor' failed]
    Jul 19 14:44:53 s3black gnome-shell[2017]: meta_screen_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
    Jul 19 14:44:53 s3black gnome-shell[2017]: meta_screen_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
    Jul 19 14:44:53 s3black gnome-shell[2017]: JS ERROR: TypeError: monitor is null#012_reposition@resource:///org/gnome/shell/ui/boxpointer.js:508:13#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012setPosition@resource:///org/gnome/shell/ui/boxpointer.js:430:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012open@resource:///org/gnome/shell/ui/popupMenu.js:866:9#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012toggle@resource:///org/gnome/shell/ui/popupMenu.js:746:13#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22#012_onEvent@resource:///org/gnome/shell/ui/panelMenu.js:138:13#012wrapper@resource:///org/gnome/gjs/modules/_legacy.js:82:22
    Jul 19 14:44:53 s3black gnome-shell[2017]: meta_screen_get_monitor_geometry: assertion 'monitor >= 0 && monitor < n_logical_monitors' failed
    Jul 19 14:44:55 s3black gnome-shell[2017]: meta_monitor_manager_get_logical_monitor_from_number: assertion '(unsigned int) number < g_list_length (manager->logical_monitors)' failed
    Jul 19 14:44:55 s3black gnome-shell[2017]: meta_workspace_get_work_area_for_monitor: assertion 'logical_monitor != NULL' failed
    Jul 19 14:44:55 s3black gnome-shell[2017]: clutter-actor.c:10049: Actor 'dashtodockDashScrollview' tried to allocate a size of 66.00 x -64.00

[Daniel van Vugt (vanvugt)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1734044, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.